This invention relates broadly to an improved system for cleaning drilling muds. More particularly, the present invention relates to an improved vacuum vent system for use with the valve member in conical separator systems.
In the prior art it is known to provide centrifuge systems for cleaning drilling mud used in oil drilling operations. For example, this technology is generally discussed in U.S. Pat. Nos. 3,243,043 issued Mar. 29, 1966 and 3,213,879 issued on Oct. 26, 1965.
Basically the rotary drilling process employs a drilling mud to bring cuttings recovered during drilling to the surface of the well. Recovered solids include sand, shale, cuttings, and heavy materials, which must be separated from the drilling mud so that the mud may be reused. Drilling mud is comprised of a variety of materials and is extremely expensive, so that reuse is mandated.
In order to separate solids, primarily sand, and other undesireable materials from drilling mud it is known to provide a centrifuge wherein dirty drilling mud is introduced at the top of a conical member under pressure. The mud is introduced tangentially within the upper confines of the generally conical interior, and it is forced into a centrifugal movement. This centrifugal movement creates an interior vacuum, which vacuum draws the cleansed material upwardly out of the apparatus for subsequent delivery to a drilling mud reservoir. Heavier materials drop down to the bottom of the centrifuge, where they may collect on an orifice closure member.
As discussed in the aforementioned patents, the orifice closure member may be biased through a counterweight to yieldably occlude the output until sufficient weight of recovered solids is accumulated so as to open the output and dump the solids. Unless the output is regulated properly vacuum will be destroyed and cleansed mud will drop through the centrifuge and be lost. Therefore, proper regulation of the outflow of solids is necessary to prevent the loss of expensive drilling mud. However, with many known prior art devices blocking or lock-up of the output orifice can occur where surges of vacuum are created during outputting of the purified drilling mud. One approach aimed at solving the vacuum lock-up problem is illustrated by U.S. Pat. No. 2,806,599 issued to Patrick on Sept. 17, 1957. The device described therein includes a vented valve closure member which constantly counteracts vacuum. Practical experience and experimentation with such devices has indicated that an alternative design is necessary. Where, for example, the separator is processing fluids where the sand has substantially been removed, cone lock-up may still occur when the vent becomes blocked in response to build-up of debris.